1 files changed, 56 insertions, 0 deletions
diff --git a/common/plugins/org.eclipse.jpt.common.utility/src/org/eclipse/jpt/common/utility/internal/transformer/NullObjectTransformer.java b/common/plugins/org.eclipse.jpt.common.utility/src/org/eclipse/jpt/common/utility/internal/transformer/NullObjectTransformer.java
new file mode 100644
index 0000000000..27e107802b
--- /dev/null
+++ b/common/plugins/org.eclipse.jpt.common.utility/src/org/eclipse/jpt/common/utility/internal/transformer/NullObjectTransformer.java
@@ -0,0 +1,56 @@
+/*******************************************************************************
+ * Copyright (c) 2012 Oracle. All rights reserved.
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0, which accompanies this distribution
+ * and is available at http://www.eclipse.org/legal/epl-v10.html.
+ * 
+ * Contributors:
+ *     Oracle - initial API and implementation
+ ******************************************************************************/
+package org.eclipse.jpt.common.utility.internal.transformer;
+
+import java.io.Serializable;
+import org.eclipse.jpt.common.utility.transformer.Transformer;
+
+/**
+ * A {@link NullObjectTransformer} will transform an object to a
+ * {@link Boolean}:<ul>
+ * <li>If the object is <code>null</code>,
+ * the transformer will return {@link Boolean#TRUE}.
+ * <li>If the object is <em>not</em> <code>null</code>,
+ * the transformer will return {@link Boolean#FALSE}.
+ * </ul>
+ * 
+ * @param <T> the type of the object passed to the transformer
+ */
+public class NullObjectTransformer<T>
+	implements Transformer<T, Boolean>, Serializable
+{
+	@SuppressWarnings("rawtypes")
+	public static final Transformer INSTANCE = new NullObjectTransformer();
+
+	@SuppressWarnings("unchecked")
+	public static <S> Transformer<S, Boolean> instance() {
+		return INSTANCE;
+	}
+
+	// ensure single instance
+	private NullObjectTransformer() {
+		super();
+	}
+
+	public Boolean transform(T o) {
+		return Boolean.valueOf(o == null);
+	}
+
+	@Override
+	public String toString() {
+		return this.getClass().getSimpleName();
+	}
+
+	private static final long serialVersionUID = 1L;
+	private Object readResolve() {
+		// replace this object with the singleton
+		return INSTANCE;
+	}
+}